Clip applying and clinching tools

ABSTRACT

A portable, pneumatically operable, magazine-fed, triggeractuated, clip-applying tool for clinching open-ended clips around adjacent wire members and having a fixed anvil jaw and a cooperating movable jaw which is actuated by a novel toggle linkage under the control of a reciprocable piston and cylinder arrangement. The direction of toggle thrust is at a right angle to the direction of jaw movement, thereby eliminating the necessity for employing bellcrank or wedge toggle actuators and the toggle linkage is such that it effects quick travel of the movable jaw for rapid clip feed, terminating in high-pressure application to the clip for final effective clinching purposes. An open-trough, clip-containing magazine feeds the clips directly to the jaw structure, thereby eliminating the usual clip transfer mechanism which places the clips in an intermediate position before they are engaged by the clinching jaws. The magazine further cooperates with the movable clinching jaw in such a manner that a positive shearing of the clips from the remaining ribbon-connected clips in the magazine takes place without the creation of ribbon fragments and consequent jaw clogging. The magazine is curved on a long radius so that the usual clip follower employed thereby tends to keep the string of clips firmly seated in the magazine trough. Convenient tool balance in the hand of the operator is a further novel feature of the tool.

United States Patent Langas et al.

[54] CLIP APPLYING AND CLINCHING TOOLS [72] Inventors: Arthur Langas,Greenview; Harrison C.

Lingle, Wilmette, both of ill.

731v Assignee: l lartco Company, Wilmette, 111. 221 Filed: 00. 21, '1969211 Appl.No.: 870,469

Primary Examiner-Andrew R. Juhasz Assistant Examiner-Leon Gilden [4 1Feb. 15,1972

[57] ABSTRACT A portable, pneumatically operable, magazine-fed,trigger-actuated, clip-applying tool for clinching open-ended clipsaround adjacent wire members and having a fixed anvil jaw and acooperating movable jaw which is actuated by a novel toggle linkageunder the control of a reciprocable piston and cylinder arrangement. Thedirection of toggle thrust is at a right angle to the direction of jawmovement, thereby eliminating the necessity for employing bellcrank orwedge toggle actuators and the toggle linkage is such that it effectsquick travel of the movable jaw for rapid clip feed, terminating inhigh-pressure application to the clip for final effective clinchingpurposes. An open-trough, clip-containing magazine feeds the clipsdirectly to the jaw structure, thereby eliminating the usual cliptransfer mechanism which places the clips in an intermediate positionbefore they are engaged by the clinching jaws. The magazine furthercooperates with the movable clinching jaw in such a manner that apositive shearing of the clips from the remaining ribbon-connected clipsin the magazine takes place without the creation of ribbon fragments andconsequent jaw clogging. The magazine is curved on a long radius so thatthe usual clip follower employed thereby tends to keep the string ofclips firmly seated in the magazine trough. Convenient tool balance inthe hand of the operator is a further novel feature of the tool.

11 Claims, 16 Drawing Figures PATENTEHFEB 151912 3.84]. ,ese

' SHEET 1 OF 3 CLIP APPLYING AND CLINCHING TOOLS The improved clipapplying and clinching tool comprising the present invention has beendesigned specifically for usein connection with the application of openU-shaped sheet metal clips to two or more wire members, as for example,in the joining of seat or bedsprings to their associated frame members.The invention is, however, capable of other uses and a tool embodyingthe principles of the present invention may, if desired, with or withoutmodification as required, be employed for clinching U-shaped clips abouta wide variety of adjacent wires, rods or other similar memberswhich areto be joined together. Irrespective however of the particular'use towhich the invention may beput, the essential features thereof are atalltimes preserved.

Specifically, the invention is concerned with a portable, manuallyoperable, magazine-fed, pneumatic tool of the general type wherein aseries of open-ended, ribbon-connected sheet metal clips aresuccessively and singlywithdrawn from a magazine containing such clipsand positioned individually about the wires or other members to bejoined together, after which the thus-positioned clip is operated uponby a pair of cooperating jaw members in such a manner as to wrap theclip about such wires and, by a clinching operation, securely tightenthe clip against the wires in binding relationship.

Conventional clip applying and clinching tools designed for the samepurpose as the tool of the present invention are possessed of certainlimitations, principal among which is the difficulty which is associatedwith transfer of the individual clips from the magazine to theclip-clinching jaw structure. Heretofore it has been considerednecessary to utilize a clip-transfer mechanism whichengages the leadingclipin the magazine and shifts the same from the magazine toan-intermediate position in the vicinity of the clinching dies or jaws,after which theselatter jaws are caused toengage the clip and clinch thesame. A wide variety of such transfer mechanisms are currently employedas constituent parts of present day clinching tools, some of themrequiring individual manipulation and others beingautomaticallyeffective once the tool cycle has Another limitation that is attendantupon the construction and use of conventional clip-clinching tools,particularly pneumatically operable tools, arises from the fact thatinvariably it has been considered necessary to cause the longitudinalaxis of the clip-containing magazine to project laterally in onedirection or another from the axis of the piston and cylinder assemblyordinarily associated with such tools for powering the clinching jaws,and sometimes additionally the aforementioned clip transfer mechanismconsumes additional lateral space. Since the cylinder casing of suchtools ordinarily constitutes the handle portion of the tool by means ofwhich the latter is manipulated or guided for clip application, a fairlywide operating area or space is required for tool manipulation and,frequently, it is difiicult to guide the toolin close operatingquarters. The present invention also obviates this latter limitation inthat it contemplates a novel tool casing design wherein not only is theclip transfer mechanism eliminated but the clip magazine lies in closeproximity to the axis of the piston and cylinder assembly'and extends inthe same general direction so that it does not offer lateralinterference with a wide range of tool movements, either in approachingthe work 7 to be done or in retreating therefrom. The specific toolcasing been initiated. In either. event, the use of suchmagazine-ejecting and clip-feedingmechanisms materially increases thecost of the tools, as well as entailing relatively complicated movinginstrumentalities which constitute apotential source of trouble insofaras the possibility of tool jamming, arising from improper ejection ofclips from the magazine or improper positioning of the clips at theclinching region of the tool for subsequent treatment by the clinchingjaws or dies, is concerned. Extremely close tolerances must bemaintained both in the manufacture of the parts and in the permanentfastening of such parts in their relative positions if cumulative errorsin clip handling are to be avoided so that the clips move squarely intotheir intermediate positions and thereafter move squarely into formingregister and cooperation with the clinching dies to effect uniformclinching operations. 7

The present invention overcomes the above-noted limitation by providinga tool in which the clip-containing magazine is so disposed with respectto the clip-clinching jaws that the leading clip in the magazine ispredisposed in the clipclinching area of the tool, properly oriented forimmediate engagement by at least one of the clip-clinching jaws as soonas these jaws are set into operation for clinching purposes. As soon asthe jaws have effected their clinching operation upon a given clip andhave been restored to their retracted clipreleasing position, the nextsucceeding clip in the magazine automatically moves into suchpredisposed and properly oriented position preparatory to effecting thenext succeeding cycle of tool operation. By such an arrangement, costlyand unreliable clip transfer mechanism is obviated. A further andobvious advantage arising from such direct application of the clips tothe clinching area, i.e., the jaw structure of the tool, resides in thefact that with the elimination of intermediate clip transferinstrumentalities, tool size and weight are decreased, thus contributingto compactness of tool design.

design of the present invention, in addition to permitting greaterfreedom of tool movement as set forth above, further enhances theportability of the tool during operation thereof in that it establishesa novel arrangement and disposition of the essential toolinstrumentalities which are common to all such tools which are designedfor the same purpose and in which, when the tool is supported from thehand of the operator, possesses a degree of stable equilibrium whereinthe jaw structure assumes a convenient disposition with respect to apair of horizontally positioned contiguous wires to be joined so thatlittle or no manual effort on the part of the operator is required toinitially align or bring the jaw structure of the tool into operativeforming register with such wires. The present tool is thus distinguishedfrom conventional tools in which an initial application of torque by thewrist of the operator is required either to raise or lower the formingjaws into forming register with the members to be joined.

A further and important feature of. the present invention resides in theprovision of a novel means for translating the power stroke of thepiston into jaw-closing movements by means of which the clips areclinched about the wires to be joined. Such means embodies apiston-instituted toggle action which differs from conventional toggleactions employed by certain clinching tools in that the effective togglethrust is at a relatively step angle with respect to the axis of pistonthrust, such an arrangement affording a number of advantages which arenot present in connection with piston-activated toggle actions whereinthe direction of piston travel is the same as the direction of togglethrust. Specifically, one such advantage, as incorporated in the presentclip-clinching tool, resides in the absorption of the reaction thrustoffered by the toggle mechanism and which reaches large proportion nearthe end of the toggle link movement by the camming action of astationary surface on the tool casing. Since this reaction thrust is ata steep angle to the piston rod which constitutes the motivating memberfor the toggle action, and which, at the time of terminal toggle actionis substantially fully extended from the piston cylinder, toggle forceswhich otherwise would bend or rupture the piston rod are assimilated bythe tool casing. Another advantage of such angular transmission of powerfrom the piston to the clip-clinching jaw structure resides in theelimination of the necessity for employing a bellcrank mechanism toguide the power input joint of the toggle links which invariably isrequired when unidirectional toggle input and output motions areemployed. A further advantage of such angular power transmission resultsin a shortening of overall tool length, and also of tool width since,obviously unidirectional transmission of power by a toggle joint from areciprocable piston to a movable toggle output member entails additivelinear space factors, one for piston travel and another for toggle linkspreading. Reduction in tool casing width is a result of the eliminationof the offset bellcrank which is necessary to insure linear continuityof piston thrust to the movable jaw element. Finally, the angulartransmission of power from the piston to the jaw structure, as embodiedin the present tool, makes possible the attainment of the aforementionedtool balance by a compact and convenient disposition of the various toolparts or instrumentalities, all in a manner that will be described indetail subsequently.

An additional novel feature of the present invention resides in thespecific construction of the clip-containing magazine by means of whichsuccessive clips are fed to the clinching jaw structure. Apart from theclosely nested disposition of the magazine with respect to the toolcasing which has previously been discussed, the magazine affordsfunctional advantages not present in connection with elongated linearlystraight magazines. According to the present invention, theclip-containing magazine is of open troughlike design and is curved on along radius, the magazine having associated therewith the usualspring-biased clip follower which yieldingly urges the clips in themagazine forwardly toward the clip-clinching jaw structure. By such anarrangement, the entire string or group of clips which are nested withinthe magazine are caused to seat squarely on the trough bottom againstupward displacement under the influence of tool vibration or shock, aswell as preventing falling of the clips from the magazine in the eventthat the tool becomes inverted, either during periods of use or idletime.

The provision of a clip-clinching tool which is relatively simple in itsconstruction and which therefore may be manufactured at a low cost; onewhich is comprised of a minimum number of parts, particularly movingparts, and which therefore is unlikely to get out of order; one which isrugged and durable and which therefore will withstand rough usage; onewhich is capable of ease of assembly and disassembly for purposes ofinspection of parts, replacement or repair thereof; one which is smoothand comparatively silent in its operation; one which is attractive inits appearance and pleasing in its design; and one which, otherwise iswell adapted to perform the services required of it, are furtherdesirable features which have been borne in mind in the production anddevelopment of the present invention.

The provision of a clip-clinching tool such as has briefly beendescribed above and possessing the stated advantages constitutes theprincipal object of the present invention. Numerous other objects andadvantages, not at this time enumerated, will readily suggest themselvesas the nature of the invention is better understood.

In the accompanying three sheets of drawings forming a part of thisspecification, one exemplary form of the invention has been shown.

In these drawings:

FIG. I is a rear perspective view of a clip applying and clinching toolembodying the present invention;

FIG. la is an enlarged sectional view taken substantially on the linelala of FIG. 1;

FIG. 2 is a side elevational view, largely in longitudinal section,showing the tool operatively positioned with respect to a pair of wiresto be joined, preparatory to effecting the clip applying and clinchingoperations;

FIG. 2a is an enlarged fragmentary sectional view taken substantiallylongitudinally and centrally through an air admission valve employed inconnection with the invention;

FIG. 2b is an enlarged sectional view taken substantially along the line2b 2b of FIG. 2;

FIG. 3 is a sectional view, similar to FIG. 2, showing the tool with theparts thereof in the positions which they assume at the completion ofthe clip-clinching operation and prior to release of the applied clip;

FIG. 4 is an enlarged perspective view of a string of ribbonconnectedclips of the type used in connection with the clipapplying tool of thepresent invention;

FIG. 5 is a perspective view showing one of the clips of FIG. 4operatively applied to and crimped about a pair of contiguous wires;

FIG. 6 is an enlarged fragmentary detail sectional view of a portion ofthe tool, the view being taken in the vicinity of the anvil region ofthe tool, and the driver or plunger being shown immediately after it hasstripped a clip from the magazine-enclosed string of clips;

FIG. 7 is a fragmentary perspective view of the structure shown in FIG.6;

FIG. 8 is a perspective view similar to FIG. 7, showing the driver orplunger in its fully advanced clip-clinching position;

FIG. 9 is an enlarged fragmentary sectional view taken substantiallyalong the line 9-9 of FIG. 2;

FIG. 10 is a fragmentary side elevational view of the structure shown inFIG. 9, the view looking in the direction and within the confines of thearrows 10-10 of FIG. 9;

FIG. 1 l is an enlarged fragmentary sectional view taken longitudinallythrough the extreme rear region of the clip magazine and illustratingthe nature of a clip follower latch mechanism employed in connectionwith the invention;

FIG. 12 is a sectional view similar to FIG. 11, showing the latchmechanism in its latched condition; and

FIG. 13 is an enlarged fragmentary sectional view taken substantiallycentrally and longitudinally through a trigger-actuated bleeder valveemployed in connection with the invention.

BRIEF DESCRIPTION Referring now to the drawings in detail and inparticular to FIGS. 1 to 3 inclusive, a portable clip applying andclinching tool constructed according to the present invention has beendesignated in its entirety at 10 and involves in its generalorganization a composite tool casing which, for purposes of descriptionherein, is stated to be comprised of a cylinder section 12, a valvesection 14, a handle section 16, a power transmission section 18, and ananvil section 20. A clip magazine 22 which is adapted to contain anelongated string of wirefastening clips C communicates at its forwardend with the anvil section 18 in a manner and for a purpose that will bemade clear presently.

The center of gravity of the tool 10 lies a slight distance below thehandle section 16 so that when this section is grasped by the operatorof the tool, a condition of balance obtains wherein the tool has astable degree of equilibrium and tends to remain in the position inwhich it is shown in FIGS. 1 to 3 inclusive and with the handle section16 and the longitudinal axis of the cylinder section 12 extendingsubstantially horizontally. The clip magazine 22 is of overall arcuateconfiguration on a relatively long radius of curvature, its dispositionwith respect to the tool body being such that when the tool is manuallysupported in its balanced condition as set forth above, the magazineprojects rearwardly and horizontally from the anvil section 20, extendsbeneath the handle section 16 and cylinder section 12, curves graduallyupwardly alongside the valve section 14 as clearly shown in FIGS. 1 and2, intersects the longitudinal axis of the cylinder section 12, andterminates at a point which lies a short distance rearwardly of the toolproper and at the uppermost level thereof. In this manually supportedbalanced condition of the tool, and because the center of gravity of thetool is only slightly below the handle section 16, the pendulum effectis slight and thus the operator may readily swing or tilt the tooleither forwardly or rearwardly, as well as sidewise in either directionif required, in order to align or otherwise bring the anvil section 20into proper register with two or more wires, rods or other members whichare to be secured by the application of one of the clips C thereto. Thismatter of tool balance when the tool is supported from the handlesection 16 constitutes one of the principal features of the presentinvention.

For convenience and clarity of description, in the remaining portion ofthis specification and in the appended claims, normal tool orientationwill be considered to correspond to the balanced condition of the toolwherein the longitudinal axis of the cylinder section 12 and handlesection 16 extends horizontally, although it will be understood that thetool may be applied to the.elements to be joined together in any desiredposition, even when the handle section 16 extends vertically ifnecessary, or when this section is inverted from its normal horizontalposition.

Briefly, the cylinder section 12 includes a cylinder proper 24 having areciprocable piston 26 therein which is operatively connected throughthe handle section 16 to a vertically movable clip-forming driver orplunger 28 disposed within the power transmission section'18.Thearrangement is such that forward horizontal movement of the pistoneffects downward movement of the plunger 28. The lower end of theplunger is provided with a movable clip-engaging jaw'30 designed forcooperation with a lower vertically aligned fixed clip-engaging anviljaw 32 associated with the anvil section 20, the two jaws, when closedupon a clip C, serving to clinch the latter about the wires W or otherelements which are to be joined together. Upon initial descent of the.plunger 28 within the toggle link section 18, the leading clip C isstripped from the string of clips within the magazine 22 and is carrieddownwardly toward the fixed lower jaw 32, after which the two jaws 30and 32 effect the clip-clinching operation, all in a manner that will bedescribed in greater detail subsequently.

The valve section 14 includes an air admission valve V] whichcommunicates through a passage 33 with the rear end of the cylinder 24,and also through. a passage 34 with a trigger-actuated bleeder valve V2having a manually operable trigger 35 associated therewith, the valve V2and trigger 35 being disposed in the handle section 16 of the tool. Airunder pressure is applied to the tool through a conventionalquickrelease fitting 36 which communicates with the valve V1. Thislatter valve is provided with a movable valve element 38 which normallyassumes a position wherein pressurized air is precluded from enteringthe cylinder 24, the valve element 38 being normally subjected to equalair pressure on opposite sides thereof. Upon actuation of the bleedervalve V2, air pressure on one side of thevalve element 38 of the valveVlis relieved so that this element shifts its position in such a manneras to admit air to .the rear end of the cylinder 24 through the passage33, thusdriving the piston '26 forwardly so as to effect the powerstroke of the plunger 28 and its associated movable jaw 30 forclip-engaging and clinching purposes. A narrow bleeder passage 39extends through the piston 26 and has a check valve 40.associatedtherewith, the bleeder passage communicating in all positions of thepiston with a variable volume air chamber or reservoir 42 forwardly ofthe cylinder 24. Air entrapped in the air reservoir acts on a limitedarea of the piston and alternately contracts and expands according tothe reciprocation of the piston, expansion of such air serving torestore the piston to its retracted position after each clip-clinchingoperation and after the trigger 35 has been released and the valve V 2has been restored to its normal condition. Restoration of the piston26-to its retracted position serves to return all of the movable toolelements and instrumentalities to their original or normal positions,thus separating the jaws 30 and 32' and releasing the clinched clip C.

THE TOOL CASING As previously set forth, the tool casing embodies theaforementioned cylinder section 12, valve section 14, handle section 16,power transmission section 18 and anvil section 20. The cylinder section12 and a limited portion of the handle section 16 is established by theprovision of a tubular casting in the form of a shell 43 which isgenerally of rectangular external configuration throughout itslongitudinal extent as shown in FIG. 1 and which tapers forwardly asshown at 44 and terminates in a thickened neck portion 46 which projectsinto the handle section 16 of the casing. The open rear end of the shellis closed by means of closure head 48 which is secured in position 'bymeans of screws 49 and which likewise is preferably in the'form of acasting. A partition wall 50 extends tranversely across the shell 43 anddivides the interior of the shell into a rear cylindrical chamber whichconstitutes the aforementioned cylinder 24, and a forward frustoconicalchamber which constitutes the aforementioned air reservoir or expansionchamber 42. This latter chamber is adapted to contain a quantity ofpressurized air which is continuously effective against the piston 26for piston return purposes, all in a manner that will be described indetail subsequently. The closure head 48 establishes the valve section14 of the tool, the valve V1 being embodied in this section in a mannerandfor a purpose that also will be set forth subsequently.

The forward end of the neck portion 46 is provided with a pair ofoppositely disposed flat relief areas 52 (FIG. 1) to which there arebolted a pair of spaced-apart sideplates 54 of irregular outline andwhich, in combination with a backplate 56 and a top plate 58, establishthe power transmission section 18. Locating pins 60 project through thevarious plates 54, 56 and 58 while through-bolt assemblies 62 hold theplates together. An L-shaped guide block 64 for the plunger 28.isinterposed between the sideplates 54 in the bottom regions thereof andis held in position by additional locating-pins 60. This guide block inaddition to performing its guiding function, also reinforces orrigidities the tool casing in the transmission section 18 thereof.Arcuate relief or clearance areas 65 are provided in the rear edges ofthe sideplates 54 to expose the trigger 35 and facilitate triggeractuation when the tool is manually supported. The anvil section 20 ofthe tool is established by the provision of a generally L-shapedblocklike anvil member 66 to whichthe forward end of the magazine 22 issecured, the member cooperating with the guide block 64 to provide anentrance throat for passage of the clips C to the jaw structure of thetool for successive cooperation .with the jaws 30 and 32 in a mannerthat will be set forth in detail when the operation of the jaw structureis set forth. The anvil member 66 is held in position between thesideplate 54 by locating pins 60. A tool casing adjunct in the form of astrap 68 is attached at one end to the rear region of the clip magazine22 and at its other end to a rearwardly projecting web 69 provided onthe closure head 48.

THE PISTON AND CYLINDER ASSEMBLY As previously stated, the cylinderproper 24 and the air return or expansion chamber 42 are disposed withinthe casting shell 43 and are separated by the partition wall 50. Thepiston 26 is of circular configuration, is slidingly sealed to the wallof the cylinder 24, and is provided with a forwardly extending tubularstem 70 which projects through a tubular boss 71 provided centrally onthe partition wall 50 and is slidingly sealed thereto. The piston 26 isfurther provided with a piston rod 72 which has its rear end regionprojecting into the stem 70 and its forward end region projecting intoand through the thickened neck portion 46 of the shell 43 and isslidably sealed therein. A fastening screw 73 holds the piston rod 72 inposition within the stem 70. The aforementioned bleeder passage 39extends longitudinally through the piston rod 72 and fastening screw 73and communicates with the interior of the cylinder 24 at its rear endand with the air expansion chamber 42 through a series of four radialpassages 74 (FIG. 2b) which normally are closed by a resilientelastomeric O-ring which surrounds the piston rod 72 and constitutes theaforementioned check valve 40. The O-ring functions to close thepassages 74 when air pressure in the expansion chamber 42 exceeds theair pressure in the cylinder 24, and to permit air to flow through thesepassages when the air pressure in the cylinder 24 exceeds that in theexpansion chamber 52. Thus, when air at full line pressure is admittedto the cylinder 24 through the passage 33 by the valve V1 due tobleeding of the passage 34 by actuation of the bleeder valve V2, thepiston will be driven forwardly until it reaches the end of its powerstroke as shown in FIG. 3, after which air will bleed through thepassage 39 in the piston and thus pressurize the chamber 42 to such anextent that when the bleeding effect of the valve V2 is terminated byrelease of the trigger 35 and the valve V1 is restored to its normalposition, the air pressure developed in the chamber 42 will act on thenarrow annulus 76 established by the extreme forward rim of the tubularpiston stem 70 and restore the piston to its retracted position as shownin FIG. 2. An air vent 78 in the forward region of the cylinder 24allows escape of air during the pressure stroke of the piston 26, aswell as admitting air to the cylinder during the return stroke.

PNEUMATIC CONTROL MECHANISM The pneumatic control mechanism foractuating the piston 26 embodies the aforementioned air admission valveV1, the bleeder valve V2, and the trigger 35.

(The Air Admission Valve) The air admission valve V1 is best illustratedin FIGS. 2, 2a and 3 and includes a fixed valve casing 80 disposed in asocket 81 formed in the closure head 48 and held therein by a roll pin82 (FIG. 2a). The valve casing 80 is provided with an inlet port 83which communicates with the quick-release fitting 36, a second port 84which communicates with the passage 33 leading to the cylinder 24, and athird port 86 communicating with the atmosphere. The valve element 38,in the illustrated form of the invention, is a free-floating elementalthough it is within the purview of the invention to spring bias thesame in a rearward direction. This element is of spoollike design andhas a first spool flange 88 which is movable bodily with the elementbetween the retracted position shown in FIG. 2 wherein air is preventedfrom passing from the quick-release fitting 36 to the passage 33, andthe advanced position shown in FIG. 3 wherein the fitting and passageare in communication with each other. The valve element 38 is providedwith a second piston flange 90 which is slidable in a chamber 92 havingcommunication through a passage 94 with the bleeder passage 34, thelatter passage being formed in the wall of the shell 43 and alsoprojecting through the reduced neck portion 46 in the handle section 16of the tool. A narrow bleeder passage 96 extends axially through thespoollike valve element 38 for the purpose of normally equalizing thepressure on opposite sides of the element, in which case the greaterarea of the piston flange 90 as compared to the area of the spool flange88 will maintain the valve element in its rearward retracted position.At such time as the pressure of air on the forward side of the valveelement 38 is relieved incident to manipulation of the bleeder valve V2,the valve element 38 will move to its advanced position, thus uncoveringthe passage 33 and allowing air at line pressure to be conducted to therear end of the cylinder 24 to initiate the power stroke of the piston26.

(The Bleeder Valve) The trigger-actuated bleeder valve V2 is shown indetail in FIG. 13 and it includes a valve casing 100 which is sealinglysecured by a roll pin 101 in a socket 102 provided in the forward endface of the reduced neck portion 46 of the cylinder shell 43. The valvecasing 100 is generally of cup-shape configuration and defines aninternal valve chamber 104 having a relatively thick front wall 106 andwithin which there is disposed a reciprocable valve element 108 designedfor sealing engagement with an O ring 110 which bears against the frontwall 106. The forward end of the valve chamber 104 communicates throughan L-shaped passage 112 with the atmosphere in the vicinity of thehandle section 16 of the tool. The valve element 108 is provided with astem 114 which is guided in a bore 116 formed in the valve body 100, theforward end of the stem being engageable with one leg of an actuator 118in the form of a bellcrank, the other leg of the actuator projectinginto a slot 120 provided in the trigger 35. The forward end of the valvecasing 100 is bifurcated as indicated at 122 for reception of thetrigger actuator 118, the latter being pivoted on a pin 124. The trigger35 has a fingerpiece 126 (FIGS. 1, 2 and 3) pivoted on a pin 128 whichextends between the sideplates 54 of the power transmission section 18,the fingerpiece projecting forwardly of the clearance areas 65 of thesesideplates where it is conveniently accessible for manipulation when thetool is supported by the handle section 16.

From the above description it will be apparent that when the trigger 35is depressed the consequent rearward movement of the valve element 108will lift the same from its seating engagement with the O-ring (FIG. 13)so that air which is disposed in the bleeder passage 34 will be bledthrough the valve V2 and its associated passage 112 to the atmosphere,thus relieving the pressure on the forward side of the piston flange 90of the valve element 38 of the air admission valve V1 and shifting thespool flange 88 of the valve body 38 to its forward position under theinfluence of live air issuing from the quick-release fitting 36 andallowing such air to be admitted to the rear end of the cylinder 24 toeffect the power stroke of the piston 26. After the power stroke of thepiston 26 and prior to the time that the trigger 35 is released, liveair is bled through the passage 39 in the piston rod 72 past the O-ringcheck valve 40 and fills the air return expansion chamber 42 for pistonreturn purposes in the manner previously set forth.

THE POWER TRANSMISSION TOGGLE MECHANISM Forward motion of the piston 26and its associated piston rod 72 is translated into downward movement ofthe jaw-carrying driver or plunger 28 by means ofa toggle mechanism ofthe elbow joint type and which is disposed between the two sideplates54, this toggle mechanism being disposed partly in the transmissionsection 18 of the tool and partly in the handle section 16 thereof. Asclearly shown in FIGS. 2 and 3, the forward end ofthe piston rod 72 ispivotally connected by a bifurcated yoke and pin connection 130 to therear end ofa composite dual toggle link 132, which constitutes thedriving link of the elbow joint, the pin carrying a roller 134 whichtravels in a shallow guideway 136 formed in the top plate 58. Theforward end of the link 132 is pivoted by a pin 138 to the upper end ofthe plunger or slide member 28 which constitutes the driver link of theelbowjoint. The opposite ends of the pin 138 travel in vertical grooves140 which are formed in the sideplates 54. The lower end of the plunger28 projects between the guide block 64 and backplate 56 so that theplunger is at all times constrained to maintain its vertical positionwithin the confines of the sideplates 54 and backplate 56. The width ofthe grooves 140 is slightly greater than the diameter of the pivot pinand the disposition of the grooves is such that during the forwardmovement of the piston 26, the toggle link 132 is maintained undercompression and the upper region of the forward edge of the plunger 28makes frictional engagement with the rear face of the backplate 56.During the return stroke of the piston under the influence of the airwhich is entrapped within the expansion chamber 42, the link 132 ismaintained under tension and, at this time, the ends of the pivot pin138 ride against the rear sides of the grooves 140 and prevent theplunger 28 from pulling away appreciably from the backplate 56.

It is to be noted at this point that the normal position of the plungeris the raised position in which it is shown in FIG. 2, such positionbeing a positive one wherein an appreciable amount of tension isretained in the toggle link 132 under the influence of the air pressurewhich is maintained within the expansion chamber 42. This air pressureis for all intents and purposes permanently maintained in the expansionchamber 42 by reason of the efficient sealing action of the elastomericO-ring seals between the piston stem and the boss 71 and between thepiston rod 72 and the neck portion 46. With a new tool, or with a toolthat has remained idle for a long period oftime, the initial on-rush oflive air at full line pressure into the rear end of the cylinder 24commences immediately to flow forwardly through the passage 39 in thepiston rod 72 and past the O-ring check valve 40 (FIG. 2b) into theexpansion chamber 42 for piston return purposes. During the time whichelapses from the time the piston reaches the forward end of its strokeuntil the operator has released the trigger 35,

an adequate supply of pressurized air will be introduced into thechamber 42 for piston return purposes. If this air does not reach fullline pressure during the first application of a clip C, the nextsucceeding operation of the tool will supply additional air to thechamber 42 and, more often than not, the second use of the tool inapplying a clip will suffice to bring the pressure of air in the chamber42 to substantial full-rated line pressure. Thereafter, this-accumulatedor stored air will serve for piston return purposes substantiallyindefinitely, even after a prolonged period of shelf life of the tool,measured in weeks, for example. Even in an instance where the sealingmeans which exists between the piston rod.72 and the neck portion 46 ofthe cylinder shell has become worn due to continued use of the tool, asmall amount of leakage of air from the expansion chamber 42 past thepiston rod may be tolerated inasmuch as each admission of air to thecylinder 24 for piston driving purposes will serve to replenish any airwhich may have escaped during a preceding cycle of tool operation.

THE MAGAZINE AND CLIPSTI-IEREFOR The details of the clip magazine 22 arebest illustrated in FIGS. 1 to 3 inclusive and 9 to 12 inclusive, whilethe nature of the clips which are capable of being loaded into themagazine is shown in FIGS. 4 and 5.

(The Magazine Contained Clips) The individual clips C disclosed hereinfor exemplary purposes are purely conventional and no claim is madeherein to any novelty associated with the same. Briefly, each clip Cformed from a flat blank of sheet metal which has been bent to U-shapeform so as to provide a semicylindrical crown portion 143 (FIG. 4) withsubstantially planar depending legs 144 and 146. When a given clip isdisposed in the magazine 22, the planes of the legs 144 and 146 extendtransversely of the magazine so that the leg 146 may be considered to bethe forward or leading leg while the leg 144 constitutes the rear ortrailing leg with respect to the direction of motion of the clip as itis fed forwardly toward the jaw structure of the tool. The rear leg 144is formed with a central generally V-shaped recess 148 therein, whilethe front leg is formed with a conformably shaped tongue 150. When theclip is clinched about a pair of wires such as have been designated at Win FIG. 5, a wrapping operation takes place wherein the crown portion142 of the clip seats on the upper wire, while the leg 144 becomeswrapped about the lower wire, and the recess 148 therein partially orfully receives therein the tongue 150 of the leg 146, the latterbecoming partially wrapped about such lower wire. Depending upon theapproach angle of the tool when applied to the wires W, thecircumferential disposition of the clinched or wrapped clip C around thewires may become shifted in one direction or the other from the preciseillustrated position of FIG. 5.

The magazine-loaded clips C, collectively, are connected together insubstantially contiguous side-by-side relationship by means of anelongated ribbon 152 which may be in the form of a length ofpressure-sensitized tape or which may otherwise be adhered to the crownportions 142 so as to produce an elongated string of the clips. Thespecific nature of the interconnected string of clips and the manner inwhich the string is formed constitutes the subject matter of ourcopending application, Ser. No. 854,037, filed Aug. 29, 1969, now US.Pat. No. 3,613,878 entitled U-CLIP ASSEMBLY, and reference may be had tosuch application for a full understanding of several forms ofinterconnected clips which are capable of being used in the magazine 22of the present tool.

(The Clip Magazine) as to present a troughlike configuration intransverse cross section and having trough sides 154 and a trough bottom156.

The front end of the magazine is secured to the anvil member 66 by abolt and bracket assembly 157. The upper edges of the trough sides 154are provided with lateral flanges 158 throughout substantially theirentire length. As previously stated, the forward open end of thetroughlike structure projects between the anvil member 66 and the guideblock 64 while the remainder of the magazine underlies the handlesection 16 and cylinder section 12 of the tool and arches upwardly sothat the rear region thereof extends alongside the valve section 14 ofthe tool and is supported by the strap 68.

A clip follower 160 is slidable in the magazine trough and carries aplate 162 which overlies one longitudinal edge of the trough. The outeredge of the plate 162 is provided with a downwardly extending flange 164(FIG. 10) which is spaced from the adjacent trough side [54 and whichcarries an outwardly projecting manipulating fingerpiece 166 (FIGS. 9and 10). The fingerpiece projects inwardly through the ear 164 andconstitutes the central axial support for an involuntarily woundconstant-tension spring coil 168, the inner end of which is suit ablysecured to the central support and the free end of which is anchored byan anchor bolt (FIGS. 1 and 9) to the forward end of the adjacentlateral flange 158. The

spring 168 serves to yieldingly urge the clip follower 160 for-.

wardly in the magazine trough to feed successive clips C to the jawstructure of the tool, the extreme forward position of the followerbeing limited by the presence of the anchor bolt 170 which is adapted tobe engaged by the forward edge of the lateral overhanging plate 162 onthe follower 160. An elongated retention strip 172 in the form of ananglepiece (FIG. la) is welded or otherwise secured to one of theflanges 158 of the magazine as shown in FIGS. 1 and 1a and serves tocapture the follower within the magazine trough against upwarddisplacement.

The rear end of the follower 160 is bifurcated as indicated at 174 inFIGS. 9, 11 and 12, the bifurcation carrying a pivoted latch member 176which is biased by a spring 178 in a counterclockwise direction asviewed in FIG. 1 1. A slot 180 in the bottom wall 156 is adapted toreceive the latch member 176 when the follower is in its extremerearward position. The latch member 176 is provided for the purpose ofholding the follower in its fully retracted position during clip-loadingoperations as shown in FIG. 12. An abutment 181 at the rear end of themagazine trough limits the extent of rearward movement of the follower160.

THE CLIP-CLINCl-IING JAW STRUCTURE Referring now to FIGS. 2 and 3, andadditionally to FIGS. 6, 7 and 8, the anvil member 66 is of unitaryconstruction and is provided with a depending leg 182, the lower end ofwhich is formed with a forwardly extending hook portion 184 presenting aflat vertical front face 186 which is interrupted by a mediallydisposed, forwardly projecting tongue 188 which extends above the levelof the face 186. The front face 190 of the leg 182 is smooth and planarand the lower region thereof merges on a curved bias with the uppertroughlike surface of the hook portion 184 to provide the aforementionedlower fixed jaw 32. The front face 190 constitutes a dropoff portionwhich is designed for sliding engagement with the tear or trailing leg144 of the leading clip C in the magazine 22, the jaw 30 normallyoverlying the clip C prior to descent of the plunger 28 as shown indotted lines in FIG. 6. The effective clip-engaging surfaces of theanvil member 66 thus assume the form of an upright .l.

As previously stated, the lower end of the plunger of slide member 28establishes the movable upper jaw 30, this jaw being in the form of adownwardly facing troughlike recess which is best seen in FIGS. 7 and 8.This jaw is slightly offset rearwardly from the midplane of the plungerand, immediately forwardly of the jaw 30, the plunger is formed with adownwardly extending slotted extension 192 having a centrally disposedvertical slot 194 therein which extends upwardly into the body portionof the plunger a slight distance its lowermost position as shown in FIG.8. The effective clipengaging surfaces of the plunger or slide member 28thus assume the form ofan inverted .I."

In the operation of the above-described jaw structure, upon initialdescent of the plunger 28, the upper jaw 30, which normally ismaintained a slight distance above the level of the crown portion 143 ofthe leading clip in the magazine 22, engages the tape-covered crownportion as shown in dotted lines in FIG. 6 and strips the leading clipfrom the flexible string of clips remaining in the magazine as shown infull lines in this view and also in FIG. 7. Thereafter, the jaw 30carries the dislodged clip downwardly and during the downward movementthereof the clip is confined between the vertical front face 190 and theslotted extension 192 of the plunger 28. It is to be noted at this pointthat because the upper jaw cavity 30 assumes the form of an inverted Jwhile the lower jaw cavity 32 assumes the form of an upright J aspreviously stated, and because the two .ls slide vertically relative toeach other and are disposed in tandem face-to-face relationship, one legof the clip C slides on the surface 190 which constitutes the stem" ofthe upright J, while the other leg of the clip moves bodily downwardlywith the extension 192 which constitutes the stem of the inverted 1"until such time as the two opposed troughs of the Js curl the legs ofthe clip about the articles undergoing joining. Thus, during actualclip-clinching operations, the clip is completely enclosed by asubstantially solid wall or cocoon of metal and is thereby maintainedsteady for accurate precision clinching. The above-describedclip-clinching jaw structure constitutes one of the principal featuresof the present clip'clinching tool.

As the clip approaches the lower fixed jaw 32, the rear leg 144 thereofis caused to curl forwardly as shown in FIG. 7, while the slottedextension 192 moves downwardly alongside the front face 186 of the hookportion 184, thus causing the depending tongue 150 (FIG. 7) of the clipC to curve inwardly on the troughlike lower jaw 32 and enter the recess148 which is provided in the rear leg 144 of the clip. The net result ofsuch clip deformation or clinching is shown in FIG. wherein the clipbecomes securely wrapped or clinched about the wires or other memberswhich are to be joined together.

It is to be noted at this point that during the initial descent of theplunger 28, the downward effective initial pressure which is exertedupon the leading clip in the magazine 22 is transmitted through theflexible ribbon 152 which overlies the clip, the downwardly facing upperjaw seating squarely upon such ribbon and pressing the same against thecrown portion 143 of the clip with impact force. As the plunger and jawcontinue to descend, the relatively sharp rear edge of the troughlikejaw 30 effects a shearing action on the ribbon, thus severing the samealong a transverse line without disturbing the position of the nextpreceding clip in the magazine 22. The severed portion of the ribbon 152is carried downwardly with the clip and, at the time the high-pressureclinching operation takes place, the severed fragment of ribbon isfurther pressed tightly against the crown portion 143 of the clip whereit remains after the upper jaw 30 has been retracted and the clinchedclip freed from the tool. By such an arrangement, no ribbon fragmentsare scattered in the jaw region of the tool and, as a consequence, thereis little danger of tool clogging, either by reason of such fragments orby clip misalignment. It should be further noted that the slottedextension 192 on the plunger 28 normally projects downwardly below thelevel of the discharge mouth of the magazine 22 so that when the plungeris in its fully raised position the clip follower 160 urges the stringof clips forwardly and causes the leading clip C to bear against therear side of the extension 192 which thus constitutes a backstop for theleading clip and maintains it in an intermediate position from which itis dislodged by the jaw 30 dur ing the initial descent thereof.Continued downward movement of such jaw conducts the clip downwardly andinto forminwing engagement with the lower jaw 32. Additional advantagesof the present jaw structure will be set forth when the operation of thetool 10 as a whole is described.

OPERATION OF THE TOOL Having thus described the structural aspects ofthe present invention, it is believed that the mode of operation of manyof the functional tool instrumentalities are apparent from the precedingdescription. However, the following brief summary of the overall tooloperation in applying a clip to a pair of wires or other elements to bejoined together will lead to a full understanding of the invention.

Considering the tool 10 with the various movable parts thereof in theirnormal positions and after the quick-release fitting 36 has beenconnected to a source of air under pressure, the operator will initiallycause the tool to be supported by the handle section 16 and the anvilmember 66 brought to bear against the wires W in the manner shown inFIG. 2. Thereafter the trigger 35 will be depressed, thus rocking thebellcrank actuator 118 and shifting the valve element of the bleedervalve V2 rearwardly from its seat on the O-ring seal and bleeding thepassage 34 so as to reduce the pressure of air in the valve chamber 92of the air admission valve V1. Such pressure reduction allows the fullline pressure of air acting on the spool flange 88 of the valve element34 to move the valve element forwardly and uncover the port 84 so thatair may flow through the air passage 33 and cylinder 24 so as to forcethe piston 26 forwardly and effect the power stroke thereof. Suchforward movement of the piston causes forward axial shifting of thepiston rod 72 which, in turn, thrusts the upper end of the dual togglelink 132 forwardly and places the latter under compression while at thesame time the pivot pins 138 slide downwardly in the slots 140 providedin the sideplates 54. This downward movement of the pin 138 forces theplunger or slide member 28 downwardly, thus moving the upperclip-engaging jaw 30 toward the lower fixed anvil jaw 32.

The operation of the jaw structure embodying the two jaws 30 and 32 hasbeen fully set forth previously but it should particularly be noted atthis point that prior to engagement of the leading clip C in themagazine 22 the compressional forces acting on the toggle link 132 arerelatively small due to the absence of a load upon the upper jaw 30 anddespite the fact that the angle of divergence existing between thebackplate 56 and the toggle link 132 is relatively steep and on theorder of 15 as shown in FIG. 2. For this reason, little resistance todownward motion of the plunger 28 is encountered. However, the downwardcomponent of thrust upon the plunger is adequate to effect stripping ofthe leading clip C from the remaining string of clips in the magazine,the shearing action on the ribbon or tape 152 being a clean one with noloose ribbon fragments being present to clog the jaw structure.

It should also be noted at this point that as the piston approaches theend of its forward stroke, the toggle link 132 tends to progressivelystraighten out" which is to say that it gradually approaches a verticalposition of alignment with the plunger and, in so doing, the toggleeffect produces a progressively increasing potential downward thrust bythe lower jaw 32, the magnitude of this thrust amounting to many timesthe magnitude of the thrust exerted by the piston. Such increasingthrust is applied to the clip by the upper jaw 30 during the clinchingoperation and is made possible by reason of the reaction force which isprovided by the top plate 58 of the tool casing against the roller 134which travels tractionally forwardly along the underneath surface of thetop plate 58 as previously described and with increasing pressurethereagainst. In the absence of such reaction force, the piston rodwhich, at the time of maximum plunger thrust, becomes substantiallyfully projected from the reduced neck portion 46, would be unable toexert the necessary downward thrust on the toggle link for proper clipclinching without bending or becoming otherwise damaged.

Finally, in connection with the feeding of the clips to the jawstructure, it should be observed that the magazine 22 delivers the clipssuccessively directly to the jaw structure or, in other words, presentseach succeeding leading or foremost clip directly to the upper jaw 30 byprojecting the clip sidewise and forwardly against the rear inside faceof the bifurcated downward extension 192 where it remains properlyoriented for engagement by the upper jaw 30 for shearing and clinchingpurposes as previously described. By such an arrangement, the use ofintermediate transfer devices which are currently used for shifting theleading clip from the magazine to a position of operative register withthe clinching jaws is eliminated.

Insofar as the clip-containing magazine 22 is concerned, the arcuatenature of this magazine, in combination with the spring-biased clipfollower 160 tends to keep the entire string of clips seated on thebottom wall 154 of the magazine against dislodgment due to normal pistonshock, as well as accidental shock incident to handling of the tool.Maintenance of the magazine within the relatively narrow lateralconfines of the casing, as distinguished from tools in which the clipmagazine projects laterally from the casing, conserves an appreciableamount of space and greatly facilitates use of the tool in small workingareas, while the arching of the magazine in an upward direction from oneend of the tool casing to the other and beneath the handle and cylindersections 16 and 18 respectively, further contributes toward toolcompactness, while at the same time contributing toward theaforementionedtool balance.

With reference to the previously described pneumatically operableautomatic piston return system, since the initial introduction of liveair at full line pressure into the air return chamber or reservoir 42takes place incident to any given depression of the trigger 35 andremains effective over a long period of time for piston return purposes,an appreciable saving in consumption of live air is effected overconventional air return systems which depend for their operation upon afresh supply of live air for each piston retraction. Furthermore, sincethe volume of the air reservoir 42 need not be large to produce apowerful rearward thrust upon the piston 26, the size of the cylindercasting, and consequently of the overall tool casing may be kept torelatively small proportions.

The invention is not to be limited to the exact arrangement of partsshown in the accompanying drawings or described in this specification asvarious changes in the details of construction may be resorted towithout departing from the spirit of the invention. For example,although the transmission section l8 of the tool has been illustratedand described as effecting a right-angle transmission of power from thepiston 26 to the plunger 28, it is within the scope of the invention tocause the effective axis of the cylinder section to extend at an obtuseangle with respect to the axis of the plunger 28 since angles whichdeviate from a right angle by as much as have resulted in satisfactorytool operation. Therefore, only insofar as the invention hasparticularly been pointed out in the accompanying claims is the same tobe limited.

Having thus described our invention, what we claim and desire to secureby Letters Patent is:

1. In a clip-clinching tool, in combination, a rigid casing defining aforward transmission section, a rear cylinder section, and an anvilsection adjacent the lower end of the transmission system, saidtransmission section including a pair of parallel sideplates, a verticalbackplate and a horizontal top plate, said plates defining a rearwardlyand downwardly opening enclosure, said cylinder section including acylinder, a

piston slidable substantially horizontally in said cylinder and a pistonrod connected to the piston and movable with the piston between aretracted position and an extended position wherein it projects into theenclosure between said sideplates, said anvil section including an anvilblock defining an upwardly facing lower jaw, a vertically disposedelongated plungerthe lower end of which defines a downwardly facingupper jaw designed for clinching cooperation with said lower jaw, guidemeans on said side plates constraining said plunger to move in avertical path between an upper position wherein.

said upper jaw is remote from the lower jaw, and a lower positionwherein said jaws are in close clip-clinching proximity to each other, athrust link for translating the horizontal movements of said piston rodinto vertical movements of the plunger, means pivotally connecting oneend of the thrust link to the forward end of the piston rod, and meanspivotally connecting the other end of the thrust link to the upper endof the plunger, the effective lengths of said thrust link and plungerbeing such that when the piston and stem are in their retractedposition, the thrust link extends at a relatively small angle to theaxis of the piston rod, ancl when the piston and stem are in theirextended position, the thrust link closely approaches a position ofvertical alignment with the plunger and the jaws as suming positions ofclose clip-clinching proximity to each other.

2. In a clip-clinching tool, the combination set forth in claim I,wherein said sideplates are provided with a pair of parallel slotstherein, and the means pivotally connecting said other end of the thrustlink to the upper end of the plunger comprises a transversely extendingpivot pin the opposite ends of which project into and are guided by saidslots.

3. In a clip-clinching tool, the combination set forth in claim 2,wherein means pivotally connecting said one end of the thrust link tothe forward end of the piston rod comprises a transversely extendingpivot pin, the piston rod closely underlies said top plate, and saidlatter pivot pin carries a roller thereon which makes tractionalengagement with the undemeath side of said top plate during forwardmovement of the piston rod to the end that said top plate assimilatesthe upward reaction thrust of the thrust link during clip-clinchingoperations.

4. In a clip-clinching tool, the combination set forth in claim 3,wherein said top plate is provided with a shallow groove therein withinwhich said roller is confined.

5. In a clip-clinching tool, the combination set forth in claim 4,wherein the disposition and width of said vertical slots in thesideplates, and the width of the plunger are such that the latter makessliding contact with the rear face of said backplate during downwardmovement of the plunger under the influence of the forward thrust of thepiston rod thereon.

6. In a clip-clinching tool, the combination set forth in claim 1including, additionally, an elongated clip-storing magazine for a stringof ribbon-connected clips underlying said rear cylinder section andhaving its forward end in communication with the open rear side of saidenclosure, a clip follower yieldingly biasing the stored clips forwardlyto project the leading clip from the magazine into said enclosure andinto the path of downward movement of said downwardly facing jaw whenthe plunger is in its upper position whereby, upon downward movement ofthe plunger, the thus projected clip will initially be engaged by saidlatter jaw and carried downwardly for subsequent clinching between saidjaws, and limit stop means disposed within said enclosure constituting abackstop for limiting the extent of projection of the leading clip fromthe forward end of the magazine.

7. In a clip-clinching tool, the combination set forth in claim 6,wherein said limit stop means is carries by and movable with theplunger.

8. In a clip-clinching tool, the combination set forth in in claim 6,wherein said magazine is channel shape in transverse cross section,opens upwardly, and is arcuate in longitudinal extent whereby thecompressional forces exerted by said follower and said backstop andacting upon the leading and the trailing clip in the string of clipsdisposed in the magazine respectively serve to maintain all of the clipsseated in the magazine trough against upward dislodgment.

9. In a pneumatically operable clip-clinching tool, in combination, apair of clip-clinching jaws which are relatively movable between closedclip-clinching and open clip-releasing positions, a piston and cylinderassembly for actuating said jaws and including a tubular casing definingan internal enclosure provided with front and rear closure walls, atransverse partition wall extending across the enclosure and dividingthe same into a rear cylinder proper and a forward air reservoir, apiston slidable axially in said cylinder between a forward advancedposition and a rear retracted position and having a piston rodprojecting completely through said air reservoir and slidably sealed inrespective openings in said partition wall and front closure wall,control means effective at will to admit live air to said cylinderrearwardly of the piston, means operatively connecting the forward endof the piston rod to said pair of jaws for translating movement of thepiston rod into jawopening and jaw-closing movements, the effective areaof the opening for the piston rod in said front closure wall being lessthan the effective area for the piston rod in said partition wall,whereby when the pressure of air in said air reservoir exceeds that insaid cylinder rearwardly of the piston, differential air pressure actingon the latter will urge the same toward its retracted position, therebeing a bleeder passage in said piston and piston rod establishingcommunication between said cylinder rearwardly of the piston and saidair reservoir in all positions of the piston for admitting live air fromsaid cylinder into the air reservoir, and check valve means associatedwith said passage for preventing return flow of air from the airreservoir to said cylinder, said cylinder being provided with a bleederopening forwardly of the piston and rearwardly of the partition wall.

10. In a pneumatically operable clip-clinching tool, the combination setforth in claim 8, wherein said bleeder passage in the piston rodincludes a series of generally coplanar radial passages which open intosaid air reservoir and a resilient O- ring encircling the piston rod andyieldably sealing the outer ends of said radial passages.

11. In a clip-clinching tool for clinching an inverted U- shaped metalclip having an arched crown and depending parallel side legs about apair of contiguous wire members, in combination, a fixed lower jawmember and an upper movable jaw member, each member being generally ofJ-shape configuration and presenting a vertical side face whichterminates in an arcuate jaw trough, said members being disposed intandem face-to-face relationship with the jaw troughs opposing eachother and with the side faces being spaced apart a distancesubstantially equal to jaw trough width, said upper member being movablevertically between a lower position wherein said jaw troughs are inclose proximity to each other in clipclinching relationship and theregions of the side faces which are disposed in the vicinity of the jawtroughs directly oppose each other in clip-confining relationship, andan upper clipreleasing position, the side face of the movable jaw memberbeing formed with a vertical relief area and the fixed jaw member beingformed with a tongue which projects laterally beyond the associated jawtrough and is adapted to project into said relief area when the upperjaw member is in its lower position.

1. In a clip-clinching tool, in combination, a rigid casing defining aforward transmission section, a rear cylinder section, and an anvilsection adjacent the lower end of the transmission system, saidtransmission section including a pair of parallel sideplates, a verticalbackplate and a horizontal top plate, said plates defining a rearwardlyand downwardly opening enclosure, said cylinder section including acylinder, a piston slidable substantially horizontally in said cylinderand a piston rod connected to the piston and movable with the pistonbetween a retracted position and an extended position wherein itprojects into the enclosure between said sideplates, said anvil sectionincluding an anvil block defining an upwardly facing lower jaw, avertically disposed elongated plunger the lower end of which defines adownwardly facing upper jaw designed for clinching cooperation with saidlower jaw, guide means on said side plates constraining said plunger tomove in a vertical path between an upper position wherein said upper jawis remote from the lower jaw, and a lower position wherein said jaws arein close clipclinching proximity to each other, a thrust link fortranslating the horizontal movements of said piston rod into verticalmovements of the plunger, means pivotally connecting one end of thethrust link to the forward end of the piston rod, and means pivotallyconnecting the other end of the thrust link to the upper end of theplunger, the effective lengths of said thrust link and plunger beingsuch that when the piston and stem are in their retracted position, thethrust link extends at a relatively small angle to the axis of thepiston rod, and when the piston and stem are in their extended position,the thrust link closely approaches a position of vertical alignment withthe plunger and the jaws assuming positions of close clip-clinchingproximity to each other.
 2. In a clip-clinching tool, the combinationset forth in claim 1, wherein said sideplates are provided with a pairof parallel slots therein, and the means pivotally connecting said otherend of the thrust link to the upper end of the plunger comprises atransversely extending pivot pin the opposite ends of which project intoand are guided by said slots.
 3. In a clip-clinching tool, thecombination set forth in claim 2, wherein means pivotally connectingsaid one end of the thrust link to the forward end of the piston rodcomprises a transversely extending pivot pin, the piston rod closelyunderlies said top plate, and said latter pivot pin carries a rollerthereon which makes tractional engagement with the underneath side ofsaid top plate during forward movement of the piston rod to the end thatsaid top plate assimilates the upward reaction thrust of the thrust linkduring clip-clinching operations.
 4. In a clip-clinching tool, thecombination set forth in claim 3, wherein said top plate is providedwith a shallow groove therein within which said roller is confined. 5.In a clip-clinching tool, the combination set forth in claim 4, whereinthe disposition and width of said vertical slots in the sideplates, andthe width of the plunger are such that the latter makes sliding contactwith the rear face of said backplate during downward movement of theplunger under the influence of the forward thrust of the piston rodthereon.
 6. In a clip-clinching tool, the combination set forth in claim1 including, additionally, an elongated clip-storing magazine for astring of ribbon-connected clips underlying said rear cylinder sectionand having its forward end in communication with the open rear side ofsaid enclosure, a clip follower yieldingly biasing the stored clipsforwardly to project the leading clip from the magazine into saidenclosure and into the path of downward movement of saiD downwardlyfacing jaw when the plunger is in its upper position whereby, upondownward movement of the plunger, the thus projected clip will initiallybe engaged by said latter jaw and carried downwardly for subsequentclinching between said jaws, and limit stop means disposed within saidenclosure constituting a backstop for limiting the extent of projectionof the leading clip from the forward end of the magazine.
 7. In aclip-clinching tool, the combination set forth in claim 6, wherein saidlimit stop means is carries by and movable with the plunger.
 8. In aclip-clinching tool, the combination set forth in in claim 6, whereinsaid magazine is channel shape in transverse cross section, opensupwardly, and is arcuate in longitudinal extent whereby thecompressional forces exerted by said follower and said backstop andacting upon the leading and the trailing clip in the string of clipsdisposed in the magazine respectively serve to maintain all of the clipsseated in the magazine trough against upward dislodgment.
 9. In apneumatically operable clip-clinching tool, in combination, a pair ofclip-clinching jaws which are relatively movable between closedclip-clinching and open clip-releasing positions, a piston and cylinderassembly for actuating said jaws and including a tubular casing definingan internal enclosure provided with front and rear closure walls, atransverse partition wall extending across the enclosure and dividingthe same into a rear cylinder proper and a forward air reservoir, apiston slidable axially in said cylinder between a forward advancedposition and a rear retracted position and having a piston rodprojecting completely through said air reservoir and slidably sealed inrespective openings in said partition wall and front closure wall,control means effective at will to admit live air to said cylinderrearwardly of the piston, means operatively connecting the forward endof the piston rod to said pair of jaws for translating movement of thepiston rod into jaw-opening and jaw-closing movements, the effectivearea of the opening for the piston rod in said front closure wall beingless than the effective area for the piston rod in said partition wall,whereby when the pressure of air in said air reservoir exceeds that insaid cylinder rearwardly of the piston, differential air pressure actingon the latter will urge the same toward its retracted position, therebeing a bleeder passage in said piston and piston rod establishingcommunication between said cylinder rearwardly of the piston and saidair reservoir in all positions of the piston for admitting live air fromsaid cylinder into the air reservoir, and check valve means associatedwith said passage for preventing return flow of air from the airreservoir to said cylinder, said cylinder being provided with a bleederopening forwardly of the piston and rearwardly of the partition wall.10. In a pneumatically operable clip-clinching tool, the combination setforth in claim 8, wherein said bleeder passage in the piston rodincludes a series of generally coplanar radial passages which open intosaid air reservoir and a resilient O-ring encircling the piston rod andyieldably sealing the outer ends of said radial passages.
 11. In aclip-clinching tool for clinching an inverted U-shaped metal clip havingan arched crown and depending parallel side legs about a pair ofcontiguous wire members, in combination, a fixed lower jaw member and anupper movable jaw member, each member being generally of J-shapeconfiguration and presenting a vertical side face which terminates in anarcuate jaw trough, said members being disposed in tandem face-to-facerelationship with the jaw troughs opposing each other and with the sidefaces being spaced apart a distance substantially equal to jaw troughwidth, said upper member being movable vertically between a lowerposition wherein said jaw troughs are in close proximity to each otherin clip-clinching relationship and the regions of the side faces Whichare disposed in the vicinity of the jaw troughs directly oppose eachother in clip-confining relationship, and an upper clip-releasingposition, the side face of the movable jaw member being formed with avertical relief area and the fixed jaw member being formed with a tonguewhich projects laterally beyond the associated jaw trough and is adaptedto project into said relief area when the upper jaw member is in itslower position.